Bearing construction



Jan. 23, 1951 A. H. DALL BEARING CONSTRUCTION 3 Sheets-Sheet 1 Filed April 6, 1945 INVENTOR. Alfie/f [7. 136111 //6[Mllq T ZZNEYS Jan. 23, 1951 A. H. DALL BEARING CONSTRUCTION Filed April -6. 1945 3 Sheets-Sheet 2 I H 1 W HU H 8 5 A -I N aims NR R T w INVENTOR. 1 Albert II. ,D all ATTDR 576' Jan. 23; 1951 A. H. DALL 2,538,746

BEARING CONSTRUCTION Filed April 6, 1945. 3 Sheets-81199125 'TTE .5.

INVENTOR.

Alberf [i D Z1 BY shown one of the various -4 of Figured}.

- Similar referencecharacters refer to similar Patented Jan. 23, 1951 UNITED STATES PATENT oFFics BEARING CONSTRUCTION Albert H. Dali, Cincinnati, Ohio, asslgnor to The Cincinnati Milling Mac Ohio; a corporation of Ohio hine Co., Cincinnati,

8 Claims. (o1. cos-73) This invention relates to hearing construction.-

One of the objects of this invention is to provide a bearing construction for a shaft or spindle which is simple, practical, and thoroughly dur-- able. Another object is to provide a construction of the above character in which friction is reduced to a minimum. Another object is to provide a construction of the above'character which is efiicient in operation regardless of whether the shaft or spindle rotates at a high or low speed and regardless of the unit load the shaft or spindle'is carrying. Another object is to provide a construction of the above character which maintains the axis of the shaft or spindle substantially centered at all times with respect to the bearing supporting surfaces. Another object is to provide a new and improved thrust bearing which is efiicient in operation and effectively, prevents longitudinal movement of the member on which the thrust bearing is mounted.

Still another object is to provide a thrust bear-- ing which operates with a minimum of friction. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is possible embodiments of this invention,

Figure 1 isa side elevation partly in section of a spindle mounted on a pair of bearings of the type to be disclosedjh'erein;

Figure 2 is a vertical section taken on the line 2-2 of Figure3; r

Figure 3 is a vertical section taken through the spindle and bearing shown in Figure 1 and is taken on the line 3-3 of Figure 2;

l-4 ofFigure 3; and,

Figur'e5 is-a vertical section taken on the line parts throughout the several views of the draw- As conducive toalclearer understandingof certain features of this .invention, it might here be pointed out that "hydrodynamic or multiple shoe bearings have certain disadvantages. One

of these disadvantages lies in the fact that no hydrodynamic films are present under the bearing shoes at zero speed, and accordingly the bearing surfaces are in metal to metal contact. Thus the starting torque is that required for metal to metal sliding and it is another object of this invention to overcome this high starting torque. Another disadvantage is that the pressure films between the shoes of a multiple shoe bearing and adjacent bearing surface are thin on the dead load side and thick on the opposite side. If an impact load, such as encountered in milling, is placed on the spindle in the direction of the thick pressure films, this results in a greater displacement of the spindle than if the load is in the opposite direction, i. e.- with the dead load because the rigidity of a, fluid film varies inversely as to its thickness to some power much greater than one. There is a further disadvantage of a hydrodynamic bearing; if it is adjusted for high speed 'under highunit loads, the clearance between other object is to overcome the above difiiculties,

as well as many others.

Referring .now to the drawings, the opposite ends of a spindle, generally indicated at l2, are

mounted on apair of bearings In and l l. Spindle I2 is driven through either gear l3 or gear [4 which are keyed to the spindle shaft. These gears are operatively connected to and drive a coupling [5 which is also mounted upon spindle l2. A thrust bearing, generally indicated at I6, is provided for resisting axial movement of spindle l2 longitudinally with respect to bearings I I] and H.

Bearing It includes a housing ll (-Figure 3) within whicha bushing, generally indicated at I8, is mounted. Bushing I8 is connected to housing ID in any suitable manner such as by screws (not shown). Within bushing I8 a second bushing, generally indicated at I9, is mounted. This bushing is connected to bushing l8 bya series of screws similar to screw 20. Bushing I! has three pockets 2|, 22, and 23 (Figure 2) therein circumferentially disposed about spindle 12. These pockets which are cut completely through the'bushing are of the same sizeand separated from each other by portions [9a, I91), and He of bushing IS). The bearing surface of bushing l9 including portionslfla, I91), and I is spaced from the spindle to provide a slight'clearance therebetween; for example, this clearance may be on the order of .002 of an inch. Tilting shoes 2!, 25, and 26 are mounted in pockets 2|, 22, and 23, respectively. These tilt- I ing shoes are identical in construction and have arcuate faces 24a, 25a, and 26a of a radius slightly greater than the radius of the spindle journal around which they are mounted. The shoes as a whole are of a length and width slightly smaller than the length and width of the pockets (Figure 3) in which they are mounted. The backs of the shoes are shaped so that their ends are spaced from bushing l8 and the shoes increase in width to the center portion at which point they are mounted upon bushing |8 by screws 21, 28, and 29 which are threaded into bores extending through bushing l8. The inner ends 21a, 28a, and 29a of the screws are not threaded and extend into similarly shaped but slightly larger bores in shoes 24, 25, and 26. The central rear portions of the shoes abutting against bushing |8 are curved with a radius of curvature slightly smaller than that of the bore of bushing l8. This permits each of the shoes to rock on the ends 21a, 28a, .and 29a transversely with respect to the bearing surface of. spindle 2 or toward and away from its axis. The outer ends of each of the shoes slant away from the spindle surface to aid the entrance of fluid beneath the shoe when the spindle I2 is turning.

A pump driven by a source of power operating whether shaft I2 is stationary or rotating, diagrammatically indicated at 3|! (Figure 3), pumps fluid from a sump, diagrammatically indicated at 3|, through conduits 32 and 33 to bore 34. Pressure in conduit 33 is maintained constant by a relief valve, diagrammatically indicated at 39. Bore 34 extends downwardly in one of the sideplates 35 of the housing of thrust bearing I6 and then extends inwardly to an annular pressure groove 36 (Figures 3 and formed in the side wall of the thrust disc, generally indicated at 31 (Figures 3 and 5.) Thrust disc 31 has a hub 31a which is keyed by key 38 to spindle l2 and thus disc 31 rotates with spindle l2.

Bores 4|, 42, and 43 extend through plate 35 at circumferentially spaced points and connect with groove 38. Bores 4| and 42 are aligned with bores extending through bushing l8 similar to bore 44 (Figure 3) with which bore 43 is aligned. The three bores in bushing l8 are connected by couplings similar to coupling 45 (Figure 3) to three resistance tubes 46, 41, and 48 extending about the bushing l8. Each of these tubes is connected by couplings, similar to coupling 49,

to one of holes 50, 5|, and 52 (Figure 2) which extend through bushing, l8 and open into pockets 2|, 22, and 23. Thus pockets 2|, 22, and 23 (Figure 2) are supplied with fluid under pressure from groove 36 (Figure 3) through separate connections to groove 36 which include resistance tubes 46, 41, and 48.

As pointed out hereinabove, pockets 2 I, 22, and

.23 are separated by dam portions l9a, |9b, and

|9c of bushing l9. Each of these dam portions has a collector groove 53, 54, and 55 (Figure 2) which extend longitudinally (Figure 3) throughout the length of the bushing [9. These grooves are connected to the annular spaces 56 and 51 at the left and right-hand ends of bushing l9, as

collecting grooves 65 and 84 in spindle l2. These grooves are connected by bores 61 and 581.0 bore 58 and a sealing ring 69 is spring pressed against the ring 60. Thus any fluid which leaks past the sealing ring 69 is collected in grooves 63 and 64 and is then directed to the sump.

In operation, the shoes 24, 25, and 26 tilt in such manner as to establish a hydrodynamic film between their bearing surfaces and the spindle l2. More particularly, assuming a rotation of the spindle in a coimterclockwise direction, as viewed in Figure 2, fluid in the pockets is urged between the shoes by the spindle, entering adjacent the ends B and advancing toward the ends A of each shoe; the shoes rock about the ends of screws 21, 28 and 29, the ends A thereof moving closer to the spindle and the ends B moving further away. Continuation of rotation in this direction creates a hydrodynamic pressure fllm between each shoe and the spindle which is of greatest intensity in the vicinity of the ends A. This prevents metal to metal contact so long as the spindle rotates and in spite of large impact loads applied to the spindle.

Additionally, fluid under pressure in pockets 2|, 22, and 23 and on the adjacent surfaces of the dam portions |9a, I91), and I90 hold the spindle free from metal to metal contact whether or not the spinde is rotating. This materially reduces starting torque and is particularly advantageous where the bearing is used on a milling machine where the machine starts and stops for each work piece. The pressure in these pockets also supplements the action of the shoes by resisting axial displacement of the spindle and further reducing friction; it also adds rigidity to the structure. When the spindle moves in response to an external load; the clearance between the spindle and the portion of bushing l9 facing the direction of such movement is decreased. Thus flow resistance from whichever of pockets 2|, 22, and 23 is facing the direction of such movement is increased to increase the pressure in these pockets. There will be the opposite action on the side from which the force is applied, i. e., increased clearance, a decrease in flow resistance, and a consequent decrease in pocket pressure. Thus the pressure in the pockets is always automatically ad-- justed to meet a load, regardless of the direction of its application; The net effect of such action is that the fluid in the pocketsis constantly resisting any ofi center operation of the spindle. The resistance tubes 46, 41, and 48 tend to maintain changes in pocket pressures as described.

Bearing (Figure 3) is basically similar in construction to bearing |0. This bearing includes a bearing housing 1| having a bushing 12 mounted therein. Bushing 12 is connected to bearing-housin 1| in any suitable manner, such as by screws. A second bushing, generally indicated at 13, is mounted within bushing 12 and is connected thereto by a series of screws similar to screw 14. Bushing 13 has an annular groove 15 therein which is aligned with a bore 16 in bushing 12. Bore 16 is connected by conduit 11 to the fluid pressure conduit 33. Bushing 12 has three bores 18, 19, and (Figures 3 and 4) which extend therethrough and which are aligned with the fluid pressure groove 15 in bushing 13. Bores 18, 19, and 8|! are connected to resistance tubes similar to resistance tube 8| by couplings similar to coupling I20 (Figure 3). These resistance tubes extend around the bushing 12 in an annular groove 82 (Figure 3) and each one is connected by a coupling similar to coupling III to boresflp'l and 80', Boi -est, Disaflkhasahub portion 131a and .isxheldiin n 8 9 11 i P $hnLfihdr-l in a set1posltion onspindle' I2 between collar H4 bushing 13. 7 These pockets. contain tllting shoes formed thereon: anda nut i I5 bearing against 9, 0, and I- which are substautiellys m in hub=,31a. flhus:.-anyklongitudinal move'ment' of construction o he tings e -in be i I spindle izistransmitted 'to thrust disc-$13 -Adand are mounted on the innerrends of adjustable Jacent pressure groove 38 '(Figures 3 and5) and" screws 0|, 92. and 0 3to rock-transversely, or cut; intodisc-31areJa seriesof circumferentially toward and from the axis ofthe spindle I spaced pockets I22a, -:I22b and I22c. These As in bearing I2,ipockets 06, 01, and. are I pockets areeconn'ected' bybores'I23, -I24',-and125" separated by dam portions 13a, 13b, and,13c of m (Figure 5) extending transversely through disc bushing 13. Each of these dam portions ,isproe, 31 to threepressurepockets I26,-'I21', "and I28-cut vided with a collector. groove 94, 05. and 96 exinto;the opposite .side' of disc 31: These pockets tending longitudinally -of bushin 13. These are substantiallygreater in size thanpockets I22a, grooves are open to the sump at their left-hand I22b, and I220 and when fluid under pressure is ends, as viewed in Figure 3, and,at their rightintroduced in, groove30,iright-'hand axial-move hand ends open into an'annular; shaped space ment of the spindle, as viewed in 'Figure 3, is I00, which is connected by bores IOI and I02 to counteracted. the sump. This bearing is provided with a cap- More particularly, such right-hand movement ping plate I03 which is connected to bushing 12 I of the spindle increases the clearance between in any suitable manner, such as by screws. This plate 35 andz disc 31 to decrease flow resistance plate has an annular groove I05ktherein which betweengroove 36'and the pockets 122a; I22b, is aligned with grooves I04 extending around and I220. Due to boresi23, I24, and I25," the spindle l2 and serves to collect any fluidwhich s e in p k ts 6. I a d 8 in r as s; passes the sealing ring I06 spring pressed against t is action lsfurther supplemented by adecreasel plate I03. Groove I05 is connected to thesump 5 in the clearance-between disc 31 andp1ateII2 through bores I01, I08, and I09. The shoes in tofurther increase pocket pressures by increasing t hearing t? i a manner simmer t t flowresistance therefrom Such increase in"presshoes in bearing I0 and as-the pockets: 88, 81, surewillsbe proportioned to the'force acting to and 88 are supplied with fi-uid under pressure urge'the p rd the ht and conse through resistance t these pockets l t quently there is van instantaneous reaction "setup to center the spindle with respect to thebearing. I90 counteract iy such movement. i

The operation of bearings. I0 and II is'sub y using bearlhgs vslmilalf o' ngs I I and stantially imm d if a fluid having a 1 1 I0,. efliclent bearing action is attained at low cosity is supplied under pressure to the pockets I Speeds and e high Starting rq e f the usual holding the tilting shoes, static friction: between hydrodynamic p Of ar ng s eliminated. the spindle and bearings is substantially reduced. When the hearing has reached op ratin speed, Also friction resulting fromloads applied to the thepfessure in the tilting S oe Dockets can be spindle during operation is diminished by the reduced to that s ry to supply-fluid to the counteracting pressures in the pockets." 'Furshoes, thus greatly reducing the use of thelubrithermore, under impact loads which are in the fi using? low o y fl d, flu d direction of the dead load, such as areencounfllction at h1ghspeediskept a 'a m nimumw I tered in milling, the hydrodynamic pressure films -Thl1$3it be seen that a; thoroug y pracs on the bearing shoes prevent metallic contact-be ticaland durable bearing construction has been tween t Shoes and t spindle. w t disclosed.aIFurthermore, a bearing construction pact load is in thevopposite direction 'or toward-i5 hasheeh disclosed Which Operates y t d having t t hydrodynanfl pres. low orhighcrates of. speed under a high unit load Sure film, displacement spindle "1 witha minimumof bearing'friction. According-' mized; the hydrodynamicvpressure m h 1y, it will be seen that the objects mentioned-' pressure in the pockets coact to hold therspindle hereinabove'aslweu as'many e e I and thus absorb the impact-load 'with 'maxiinum. Y a rigidity.m I .0 311' I 1;.1 1 m ny-:- po ib1 mb0diments 'mayb'e made- A further d nt t z h d of the" mechanicalf'featuresof thefaboye in'vehlies in the fact that-the multiple'shoebearings ig e' fide may be adjusted t m t elearaherforhigh thezembodiment'above'setiorth';alliwithout def speed operation'and yet at low speed the prespartingfrom 'scOpe 0 th'ihventibhi i l sure films on the-bearing shoes support an "in i pact load in thexdirection -of the dead load and the fluidin the'pressure pocket 'on the'opposit'e side ofsthe'spindletsupports impact loads in-the opposite. directional When the. spindle is run 'at a high speed,: the-hydrodynamicrbearing shoes sup port loads regardless lofgthea. direction finai'whibh they are applied, rfor: at; this \timetpressure filmszx exist betweemall 'sides' o the shoes. ,i Referringnowgto-thrust bearing- I6; its housing plate 35 is -vconnectedito bushing:Iagby'afserieszo 1 screws -;I I {Figure -:-An:;an'nular gringrl :II positioned tbetween: sideplate 235w andfsaa sidepl'a tially paced fro I I 2 of the thrust bearing housing-: :Platesis35t-andat 0 "flagtlfijgfifidh'gd I I2 andzring'slii are held1 in ass mbled-relation pocket being"spacedfroin thee'd es f-saidl ship by aseriesgofz screws-113;. ;':-'Ihe':;\ividth of iringfi :0: I I I is slightly greater ;than' the thicknesskof-tthrustf disc 31 and rthusaimaintainszainner. wallszaofr-platesi 35 nd II? paced slightly fr m di 7- flow restriction positioned in each of said channels forming a. resistance to flow of fluid into each pocket, said clearance space forming a resistance to the fiow of fluid from said pockets to create a film of fluid around the circumference of said journal member under sufiicient pressure to maintain said journal member out of contact with said bearing member under static conditions, and a plurality of bearing shoes rockably mounted on said bearing member at points spaced around the circumference of said journal member, said bearing shoes being mounted adjacent said journal member to generate a hydrodynamic fllm between the shoes and the journal member upon rotation of the journal member whereby the action of said hydro-dynamic film supplements the action of said film of fluid under dynamic conditions.

2. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being clearance space between the bearing surfaces of said members to allow for relative lateral movement between said members, the bearing surface of said bearing member having a plurality of pockets therein, said pockets being circumferentially spaced from each other around the bearing surface of said last-mentioned member, said pockets being spaced from the edges of the bearing surface of said bearing member, a closed separate channel for each pocket solely connected to said pocket and to a source of fluid under pressure, a flow restriction positioned in each of said channels forming a resistance to flow of fluid into each pocket, said clearance space forming a resistance to the flow of fluid from said pockets to create a film of fluid around the circumference of said journal member under sufficient pressure to maintain said journal member out of contact with said bearing member under static conditions, and a plurality of bearing shoes rockably mounted on said bearing member at points spaced around the circumference of said journal member, said bearing shoes being mounted adjacent said journal member to generate a hydro-dynamic film between the shoes and the journal member upon rotation of the journal member whereby the action of said hydro-dynamic film supplements the action of said film of fluid under dynamic conditions.

3. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being clearance space between the bearing surfaces of said members to allow for relative lateral movement between said members, the bearing surfaces of said bearing member having a plurality of pockets therein, said pockets being circumferentially spaced from each other around the bearing surface of said last-mentioned member, said pockets being spaced from the edges of the bearing surface of said bearing member, a closed separate channel for each pocket solely connected to said pocket and to a source of fluid under pressure, a fiow restriction positioned in each of said channels forming a resistance to flow of fluid into each pocket, the clearance space between the bearing surfaces forming a resistance to the flow of fluid from said pockets to create a film of fluid under pressure around the circumference of said journal member under sufiicient pressure to maintain said journal member out of contact with said bearing member under static conditions, and a plurality of bearing shoes rockably mounted in said pockets on said bearing member, said bearing shoes being mounted adjacent said journal memher to generate a hydro-dynamic film between the shoes and the journal member upon rotation of the journal member whereby the action of said hydro-dynamic fllm supplements the action of said film of fluid under dynamic conditions.

4. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being clearance space between the bearing surfaces of said members to allow for relative lateral movement between said members, the bearing surface of one of said members having a plurality of pockets therein, said pockets being circumferentially spaced from each other around the bearing surface of said last-mentioned member, said pockets being spaced from the edges of the bearing surface of said last-mentioned member, a closed separate channel for each pocket solely connected to said pocket and to a source of fluid under pressure, a flow restriction positioned in each of said channels forming a resistance to flow of fluid into each pocket, said clearance space forming a resistance to the flow of fluid from said pockets to create a fllm of fluid around the circumference of said journal member under sufificient pressure to maintain said journal member out of contact with said bearing member under static conditions, a series of bearing shoes, and means mounting each shoe for rocking movement in a plane transverse to the axis of said journal member, said shoes rocking about fixed lines parallel to the axis of said journal member so that rotation of the journal member generates a hydro-dynamic film between said shoes and said journal member whereby the action of said hydro-dynamic film supplements the action of said fllm of fluid under dynamic conditions.

5. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being clearance space between the bearing surfaces of said members to allow for relative lateral movement between said members, the bearing surface of said bearing member having a plurality of pockets therein, said pockets being spaced from the edges of the bearing surface of the bearing members and being in substantial circumferential alignment around the bearing Surface of said last-mentioned member, the clearance space between said bearing surfaces forming the principal path for escape of fluid from each pocket, a closed separate channel for each pocket solely connected to said pocket and to a source of fluid under pres sure, a flow restriction positioned in each of said channels forming a resistance to flow of fluid into each pocket, said clearance space forming a re sistance to the fiow of fluid from said pockets to create a film of fluid around the circumference of said journal member under suflicient pressure to maintain said journal member out of contact with said bearing member under static conditions, and a plurality of bearing shoes rockably mounted in said pockets, said bearing shoes rocking on axes spaced from the bearing surface of said journal member, said axes being parallel to the axis of said journal member so that rotation of the journal member generates a hydro-dynamic film between said shoes and said journal member whereby the action of said hydro-dynamic film supplements the action of said film of liquid under dynamic conditions.

6. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being clearance space between thebearing surfaces of said members to allow for relative lateral movement between said members, the bearing surface of one of said members having a plurality of pockets therein, said pockets being circumferentia'lly spaced from each other around the bearing surface of said last-mentioned member, said pockets being spaced from the edges of the bearing surface of said last-mentioned member, a closed separate channel for each pocket solely connected to said pocket and to the pressure side of a pump, a hydraulic resistance positioned in each of said channels forming a resistance to flow ofliquid into each pocket, the clearance space between said bearing surfaces forming a resistance to flow of liquid out of each pocket, said pump continuously supplying liquid to each pocket through said channels under pressure to create and maintain a journal supporting film of liquid in said clearance space under pressure to separate said bearing surfaces under static conditions, and a plurality of bearing shoes, means rockably mounting said bearing shoes on said bearing member at points spaced from and around the bearing surface of said journal member, said bearing shoes being mounted to rock on axes parallel to the axis of said journal member so that rotation of the journal member generates a hydrodynamic film of'liquid between the shoes and the journal member whereby the action of said hydro-dynamic film supplements the action of said liquid film under dynamic conditions.

7. In bearing construction, in combination, a bearing member, a journal member rotatably mounted within said bearing member, there being 1 clearance space between the bearing surfaces of said member to allow for relative lateral movement between said members, the bearing surface of said bearing member having a plurality of pockets therein spaced from the edges of the bearing surface of said bearing member, said pockets being equidistantly spaced from each other and in substantial circumferential align-'.

ment around the bearing surface of said lastmentloned member, a closed separate channel for each pocket solely connected to said pocket and to the pressure side of a. pump, a hydraulic resistance positioned in each of said channels forming a resistance to flow of liquid into each pocket, said pump continuously supplying liquid to said pockets under pressure, the pressure of the liquid in said pockets maintaining the journal member out of contact with said bearing member under static conditions, said clearance space forming a resistance to the fiow of fiuid from said pockets to create a film of fluid around the circumference of said journal member under sufllcient pressure to maintain said journal member out of contact with said bearing member under static conditions, and a bearing shoe rockably mounted in each pocket so that rotation of the journal member generates a hydro-dynamic film between the shoes and the bearing surface of the journal member whereby the action of said hydrodynamic film supplements the action of said liquid film under dynamic conditions.

8. In bearing construction, in combination, a bearing member, a journal member rotatably mounted on said bearing member, there being clearance space ofoil film dimensions between the bearing surfaces of said members to allow for relative lateral movement between said members, the bearing surface of said bearing member having a plurality of pockets therein spaced from the edges of the bearing surface of said bearing member, said pockets being equidistantly spaced from each other and in substantial circumferential alignment around the bearing surface of said last-mentioned member, a closed separate channel for, each pocket solely connected to said pocket and to a source of lubricant under pressure, a hydraulic resistance positioned in each of said channels forming a resistance to flow of lubricant into each ocket, said source of lubricant continuously supplying lubricant under pressure to each pocket, the clearance space between said bearing surfaces forming the sole means of escape of lubricant from each pocket, said clearance space forming a resistance to the flow of fiuid from said pockets to create a film of fluid around the circumference of said journal member under sufficient pressure to maintain said journal member out of contact with said bearing member under static conditions, a plurality of bearing shoes, and means mounting a shoe in each pocket for rocking movement in a plane transverse to the axis of said journal member so that said bearing shoes rock about fixed lines parallel to said journal member, the bearing surfaces of said shoes facing and being complementary to the bearing surface of said journal member so that rotation of said journal member generates a hydro-dynamic film between said shoes and said journal member whereby the action of said hydro-dynamic film supplements the'action of said oil film under dynamic conditions.

' ALBERT H. DALL.

REFERENCES CITED The following references are of record in the file of'this patent:

UNITED STATES PATENTS 4 Number Name Date 1,086,308 Parsons Feb. 3, 1914 1,906,715 Penick May 2, 1933 2,003,316' Shein June 4, 1935 2,160,778 Dall May 30, 1939 2,348,928 Sampatacos May 16, 1944 

